Hydraulic piston



Get. 16, 1951 E. cHRlsTENsEN HYDRAULIC PISTON Filed DSC. 5. 1947 ,I A Q v .Nllll Patented ct. 16, 1951 HYDRAULIC PISTON Elman Christensen, Montreal, Quebec, Canada Application December 5, 1947, Serial No. 789,944 In Canada September 17, 1947 9 Claims.

The invention relates to improvements in a hy-v draulic piston as described in the present specification and illustrated in the accompanying drawings that form a part of the same.

The invention consists essentially of the novel features of construction, as pointed out broadly and specifically in the claims for novelty following a description containing an explanation in detail of an acceptable form of the invention.

The objects of the invention are to devise a hydraulic piston particularly adapted for hydraulic brakes on motor vehicles; to furnish a hydraulic piston having means adapted to be expanded so as to always be a perfect t within its cylinder, thus rendering the same leak-proof; to offer a hydraulic piston including means adapted to be expanded as it becomes Worn, thusA eliminating any slack or looseness with respect to the cylinder for same; to make a hydraulic piston which will be simple in construction and inexpensive to manufacture; to construct a hydraulic piston which may be easily assembled in position in a cylinder or removed therefrom; and generally to provide a hydraulic piston which will be durable. dependable and efficient for its purpose.

' In the drawings:

Figure 1 is a cross section along the longitudinal axis of a hydraulic piston assembly according to the invention with the associated brake control arm in elevation.

Figure 2 is an exploded view showing the varous parts of the hydraulic piston.

Like numerals of reference indicate corresponding parts in the various figures.

Referring to the drawings, the hydraulic piston, as indicated by the numeral I0, is accommodated in the hydraulic cylinder II. This cylnder is of the conventional type having an inlet I2 and bore I3.

The hydraulic piston IIJ consists of the piston head I4 which is cylindrical in shape and has a shoulder or body I5 extending around the forward portion thereof. The forward portion of the piston head I4 has a conical hollow socket portion I6 extending thereinto which is adapted to engage the end of the brake control armr I'I.

The expansion ring I8 is of a resilient material, preferably rubber, and nts over the piston head I4 adjacent to the shoulder I5 of same. This expansion ring I8 consists of an outer annular Wall I9 and inner annular wall 20, which are joined at the front or base portion thereof and are integral therewith. y

The annular space 2|, between the outer and inner walls I9 and 2U, is open at the rear thereof and slightly V-shaped when in a normally free position. The rear edge of the outer wall I9 is chamfered or beveled on the inside thereof so as to facilitate engagement of the expansion sleeve 22 therewith.

AThe expansion sleeve 22 is slidably fitted over the rear portion of the piston head I 4. The projecting portion or nose 23 having an outer surface like that of a truncated cone at the forward or leading end of this expansion sleeve 22 is adapted to enter the annular space 2I between the outer and inner walls I9 and 20 of the expansion ring I 8.- The inner wall of the expansion sleeve 22 extends partially over the inner Wall 2l) of the expansion ring I8, and the rear portion of the inner or leading wall or end of this sleeve has a shoulder or step 24 which overlies the end of the same, thus forming with the projecting portion a recess which is adapted to accommodate the inner wall 20 of the expansion ring.

The ridge 25 is formed around the periphery of the expansion sleeve 22, and at the rear or base end thereof and, in .cooperation with the rear portion of the piston head I4, forms an annular groove 26 therebetween. A plurality of holes or passages 2l extend from this annular groove 26 through the expansion sleeve and the same are parallel to the axis of the hydraulic piston I0. Y

The conical compression spring 28 is adapted to exert an outward pressure on the expansion sleeve 22 so as to t the expansion ring I8 against the bore I3 of the cylinder II. The large end of this conical spring iits in the groove 26 of the expansion sleeve 22, while the opposite end of the same bears against the rear wall of the cylinder.

The brake control arm I I, which engages in the socket portion I6 of the piston head I4, is held under tension by therspring'29 which tends to draw the same inwards towards the cylinder II at all times.

In the operation of the invention, the fluidV enters the cylinder through the inlet I2 and is adapted to bear on the rear 'of the piston I0 so as to force the same forward,thus actuating the brake control arm I1. When the pressure in the cylinder vII is released the tensionspring 29 returns the brake control arm I'I to its original pcsition, thus moving the piston I0 inward in readiness for a second operation. As the piston III moves inward and outward with respect to the cylinder, the expansion sleeve 22, pressing against the expansion ring I8, forces the latter outward against the wall of the cylinder at all times.

It will be understood that while the piston, as described herein, is particularly adapted for use with hydraulic brakes, with slight modifications the same could be used for many other purposes without departing from the spirit of the invention.

It will be seen from the foregoing that a piston for hydraulic brakes and the like has been designed that will continue to operate faultlessly, despite wear on the same, and which will remain leakproof at all times.

What I claim is:

1. An expansion sleeve useful in a piston and piston-sealing structure for reciprocation in a fluid-containing cylinder in which the piston has a cylinder-engaging body and a central cylindrical projection of reduced diameter extending axially from the body, and a resilient expansion ring fitted over the projection and having base portions abutting the piston body and engaging the piston projection, and an outer annular wall for engaging the cylindersaid outer wall extending from said base portions and having an inner side spaced from the portions engaging the piston projection, the said expansion sleeve including a solid annular body having an inner side, an outer side, and adjoining the sides a leading end and a base end, the inner side including an inner annular face circumferential to the sleeves longitudinal axis as a center constituting the diametrically innermost part of the sleeve and deiining a central piston-receiving opening adapted to receive a piston projection for relative axial sliding movement, the outer side including an outer annular face circumferential to the sleeves longitudinal axis as a center and adapted to be juxtaposed to said cylinder wall, the body intermediate the inner and outer faces constituting a connection-free spacing member adapted to intervene said cylinder wall and said piston projection, the base end including a face adapted to receive external pressure for urging the sleeve towards the said expansion ring on the piston, the leading end including an annular nose projecting axially of the sleeve and having a face inclined inwardly away from said outer side towards said inner side and adapted to engage the inner side of the outer wall of the expansion ring, the said nose having a tip spaced inwardly from the outer face whereby it isV adapted to lie within the outer wall of the expansion ring. Y

2. An expansion sleeve according to claim 1 in which the base end is stepped annularly to forma pair of annular faces at different levels with a riser portion therebetween and to engage the end of a coil retaining spring urging the sleeve towards the expansion ring.

3. An expansion sleeve according to claim 1 in which the inner and outer faces are cylindrical.

4. An expansion sleeve adapted for use in combination with a piston and piston sealing structure in a fluid-cylinder of the type wherein said piston has a cylinder-engaging body and a reduced concentric cylindrical projection extending axially from the body, anda resilient expansion ring fitted over the piston projection having a base portion abutting theV piston body and concentric spaced apart inner and outer annular walls ex-l tending from said base portion and engaged with said piston projection and cylinder respectively, said expansion sleeve comprising an annular body having an inner side, an outer side, a base and a leading end, said outer side having a cylindrical face surrounding the outer periphery and adapted to operatively t within said cylinder, said inner side having an inner cylindrical face concentric with and spaced apart from said outer face to lid constitute a centrally disposed piston-receiving opening adapted to accommodate said piston projection for sliding axial movement relative thereto, the body intermediate the inner and outer faces constituting a connection-free spacing member adapted to intervene said cylinder wall and said piston projection, the said leading end having an annular nose projecting axially of said sleeve and concentrically with said inner and outer faces, said projecting nose having an outer face tapering inwardly towards said sleeve inner face to terminate in a narrow annular tip, said tapering nose outer surface being adapted to engage the inner surface of said expansion ring outer annular wall with said annular tip disposed between said expansion ring inner and outer annular walls, the inner face of said tapering nose including an annular step extending outwardly from the inner cylindrical face of said ring to form with the nose an annular recess adapted to accommodate said expansion ring inner annular wall.

5. An expansion sleeve as claimed in claim 4, wherein said base has a face transverse to said sleeve inner and outer faces including a recessed spring seat.

6. An expansion sleeve useful in a piston and piston sealing structure for reciprocation in a fluid-containing cylinder in which the piston has a cylinder-engaging body and a central cylindrical projection of reduced diameter extending axially from the body, and a resilient expansion ring fitted over the projection and having base portions abutting the piston body and engaging the piston projection, an outer annular outwardly-sloping wall for engaging the cylinder, said outer wall extending from the base portions and having an inner side extending from the base portions engaging the piston projection, the said expansion sleeve including an annular body having an inner side, an outer side and adjoining the sides a leading end and a base end, the inner side including an inner cylindrical face circumferential to the sleeves axis as a center defining a central piston-receiving opening adapted to receive a piston projection for relative axial sliding movement, the outer side including an outer cylindrical face circumferential to the sleeves axis as a center adapted to be juxtaposed to the cylinder wall, the body intermediate the inner and outer faces constituting a spacing member adapted to intervene the cylinder wall and the piston projection, the base end including a face adapted to receive pressure for urging the sleeve towards the expansion ring on the piston, said base end being stepped to form a pair of annular faces at different levels with a riser portion therebetween to engage the end of a coil spring, the leading end including an annular nose projecting axially of the sleeve and having a face inclined inwardly away from the outer side towards the inner side and adapted to engage the inner side of the outer wall of the expansion ring, the said nose having a tip spaced inwardly from the outer face whereby it is adapted to lie inside the outer wall of the expansion ring, the leading end also including an annular step having a face extending outwards from the inner side to said nose, ther nose thus being offset from the axial extrapolation of said inner face to form with the step an annular recess to accommodate an inner wall of an expansion ring.

'7. An expansion sleeve as claimed in claim 6 vwherein there are a plurality of spaced apart openings constituting iiuid passages extending throughsaidlannular body from said base end to the annular step provided on said leading end.

8. A piston and piston sealing structure for reciprocation in a fluid-containing cylinder in which the piston has a cylinder-engaging body and a central cylindrical projection of reduced diameter extendingaxially from the body and a resilient expansion ring slidably iitted over the projection and having base portions abutting the piston body and engaging the piston projection, and an outer annular wall engaging the cylinder, said outer wall extending from said base portion and having an inner side spaced from the portions engaging the piston projection, an expansion sleeve, a coil spring in said cylinder adapted to engage said expansion sleeve, said expansion sleeve including an annular body having an inner side, an outer side, and adjoining the sides a leading end and a base end, the inner side including an inner face circumferential to the sleeves axis as a center dening a central piston-receiving open- L ing receiving said piston projection for relative axial sliding movement, the outer side including an outer face circumferential to the axis of the sleeve as a center and adapted to be juxtaposed to a cylinder wall, the body intermediate the inner and outer faces constituting a spacing member adapted to intervene said cylinder wall and said piston projectionI the base end including aconfil nection-free face adapted to seat said spring, the leading end being connection-free and including an annular nose projecting axially of the sleeve and having a face inclined inwardly away from the outer side towards the inner side and adapted to engage the inner side of the outer wall of the expansion ring, the said nose having a tip spaced inwardly from the outer face whereby the tip lies within the outer wall of the expansion ring.

9. A piston and piston-sealing structure, according to claim 8, wherein said expansion sleeve is provided with at least one uid passage extending through the sleeve from said base and to said leading end.

ELMAN CHRISTENSEN.

REFERENCES CITED The following references are of record in the le of this patent: s

UNITED STATES PATENTS Number Name Date 1,721,986 Christensen July 23, 1929 1,945,153 Marsh Jan. 30, 1934` 2,059,729 Dick Nov. 3, 1936 2,093,062 Watson Sept. 14, 1937 2,149,294 Huck Mar. 7, 1939 2,250,011 Dayton July 22, 1941 

